Wheelchair users constantly encounter difficulties while traversing various terrains during their daily activities. One specific problem a wheelchair user faces is caster drift while traversing side-sloped surfaces. As the wheelchair moves across a side-sloped surface, caster wheels tend to rotate down the slope (see e.g., FIG. 1). The user's downward limb must work very hard to keep the wheelchair climbing the incline or merely traveling straight across the side-sloped surface. This can result in pain or injury to the overworked limb.
It is advantageous to eliminate the great force the user must exert on his or her downward limb for safety reasons. One particular design created for such purposes is U.S. Pat. No. 6,607,250, entitled “Caster block and wheel lock for wheelchair”. This reference features a locking mechanism that can be used to eliminate caster wheel rotation. Once engaged, this device locks the caster in the trailing position and fixes the path of the wheelchair. Although this system prevents caster drift, it also severely limits the viability of the caster for indoor use, on uneven surfaces, or in any condition under which regular turning is required. In contrast, the caster and caster system of the present invention allows users to turn the wheelchair or other device and make changes to the path of travel, while the caster is engaged and while still preventing caster drift (see, e.g. FIG. 2, where the path of a device using the caster and caster system of the present invention does not follow the slope).
Outside of the wheelchair realm, delivery persons and others using carts and dollies frequently encounter trouble turning or navigating the related art devices, especially if the devices are heavily loaded. Further, because of caster drift, materials can fall off of the cart or dolly while the user is attempting to maintain a straight course on a sloped surface.
Additionally, consumers frequently encounter wheel flutter in shopping carts because the current caster stems are freely rotating and somewhat loose fitting within the caster mount. This wheel flutter causes the entire cart to shake and/or become difficult to navigate.
The present invention overcomes the disadvantages of the related art as discussed in detail below.